Null annotations and Inspect code... Follow

Hi all,

I would like to use the Null annotations from Jetbrains and use the Code inspection to find errors,
but it seems I'm doing something wrong because I got no meaning full warnings while I'm coding
and also none during Code inspection...

I'm quite new with IntelliJ so most probably I'm doing something wrong.

Here is a test class where I would expect to get some warnings while I'm typing them, but at the least
when I trigger a Code inspection:

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.Random;

public class TestNullable {

    public void safeFoo(@NotNull Object aValue) {
        aValue.hashCode();
    }

    public <T> @NotNull T ensureNotNull(@NotNull T aValue, String aMessage) {
        if(aValue==null) {
            // I would expect to get here a warning that I unnecessarily do check for null
            // but I would also like to know how to do it nonetheless without getting a warnign
            throw new IllegalArgumentException(aMessage);
        }
        return aValue;
    }

    public void unsafeFoo(@Nullable Object aValue) {
        aValue.hashCode(); // I would have expected a warning or error here, because I provoke a NPE 
    }

    public void callingFoo(@Nullable Object aValue) {
        // I would expect an warning that I use a @Nullable object in place of a @NotNull object without checking for not nullness
        unnecessaryNullCheck(aValue);

        // same as above
        safeFoo(aValue);

        unsafeFoo(aValue);
    }

    public void unnecessaryNullCheck(@NotNull Object aValue) {
        if(aValue!=null) {
            System.out.println(aValue+" is not null");
        }
    }

    public static Object generateRandomNull() {
        return (new Random().nextBoolean())
                ? null
                : new Object();
    }

    public static void main(String[] args) {
        new TestNullable().callingFoo(generateRandomNull());
    }
}

Best regards,
Dieter